Fix some warnings (on cygwin) to allow -Werror

Fix some warnings (on cygwin) to allow -Werror

When printing valuds of type uint32_t, we should use PRIu32, and should
not assume that it is unsigned int.  On 32-bit platforms, it could be
defined as unsigned long. The same caution applies to ntohl().

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>